1. Field of the Invention
This invention relates generally to a urea adsorbent and, more particularly, to a novel polymer-based urea adsorbent suitable for use as an artificial kidney.
2. Description of the Prior Art
Artificial kidneys currently used include those of a dialysis type, filtration type, adsorption type and enzyme-fixation type. While these known artificial kidneys have certain merits, they suffer from some drawbacks too. Thus, there have not been developed yet artificial kidneys satisfactorily used for chronic or acute kidney troubles.
For example, an artificial kidney of a dialysis type, which is now most widely used, constantly requires a fresh dialysate. Further, the artificial kidney of this type is generally large in size and is inconvenient because patients are inevitably restrained in a hospital for a long time.
An artificial kidney of a filtration type has a great drawback because serum containing useful components is discarded together with effete matters.
An artificial kidney of an enzyme-fixation type, which is recently developed rapidly, has a problem of the inactivation of the enzyme at or after the fixation of urease. In addition, its performance is susceptible to environment conditions such as temperature and acidity.
An artificial kidney of an adsorption type is convenient because it is small in size and light in weight. However, the adsorbent, generally activated carbon, is not effective for the adsorption of urea which is a main ingredient secreted in urine, though it effectively adsorbs organic effete or waste matters.
At present, it has become an important problem to develop a urea-removing substance for use in an artificial kidney of an adsorption type. Oxystarch (Kobunshi Ronbunshu 39, 629) and a product obtained by reaction of a hydrazide-containing polymer with formaldehyde or glyoxal (Publication of Unexamined Japanese Patent Application No. 69489/1976) have been proposed as such an adsorbent but are not satisfactory in practice.